DESCRIPTION (Adapted from the application): Primary pulmonary hypertension of the newborn (PPHN) is an important cause of morbidity and mortality in the neonatal population. Current treatment regimens involving the use of nitric oxide gas are cumbersome to implement, hazardous to personnel, and systemically toxic to the infants. The present proposal seeks to develop in a porcine model of PPHN the lead compound of a class of nitroxide donors that would be administered locally by instillation into the trachea, and that would locally liberate short-lived nitric oxide into the pulmonary vasculature. It is hypothesized that this approach would produce local vasodilatation without systemic side effects and without the problems of delivery of a gaseous agent to infants. PROPOSED COMMERCIAL APPLICATION: There is no convenient, safe, and inexpensive treatment for primary pulmonary hypertension of the newborn. Estimated worldwide gross sales after market entry and maturation (4 years after FDS approval ) are $200 million per annum.